Decorative laminate surface coverings can be formed into sheets or individual tiles. Typically, in the manufacture of a resilient floor covering, a wear layer is combined with a substrate and resin to form the resilient sheet or tile. The substrate usually comprises a felted or matted fibrous sheet of overlapping, intertwined filaments or fibers. A substantially uniform layer of a liquid or semi-liquid resinous composition containing a synthetic polymeric material, usually an ungelled polyvinyl chloride plastisol and a blowing or foaming agent is typically applied to the substrate. The liquid or semi-liquid plastisol vinyl resin composition is subsequently firmed or gelled at an elevated temperature. This gelled plastisol may be printed with a decorative pattern or design having a blowing or foaming inhibitor for chemically embossing the substrate.
Typically, a texture may be either mechanically embossed by pressing a pattern/texture into the surface covering or chemically embossed by using foam retarding agents to restrict expansion of a foamable layer in specific regions of the design. Furthermore, both methods may be used in combination.
Mechanical embossing is the earlier of the two described embossing methods and requires the use of suitably engraved or etched plates or rolls which press against and into a resinous product or surface covering under relatively great pressure to obtain a desired embossed decorative or textured surface. An embossing roll or plate can only impart an embossed pattern corresponding to the etched or engraved pattern on the plate or roll. Often, the engraved pattern is made to create an embossed decorative texture that is in register with a printed design located on the surface covering.
Alternatively, a surface covering may be both mechanically and chemically embossed as described in U.S. Pat. Nos. 4,022,643 and 6,114,008, and Japanese Patent Publication # 63-33430 incorporated herein by reference. This reference includes coating a backing layer with a foamable layer, and adding a print layer to it. The print layer forms a design and a portion of the design is formed with a retarder composition. A thermoplastic wear layer is applied onto the print layer and cured by heat at a temperature sufficiently high enough to expand the foamable layer. The areas of the design layer where the retarder composition is applied are also chemically embossed during such curing. The wear layer is then mechanically embossed to have a surface texture in the wear layer overlying the unrestricted/up areas. Optionally, a top coat can be applied to the wear layer before curing and expanding the foam, and the top coat can be mechanically embossed.
Despite the known methods for making an embossed surface covering, there is a need for a method for mechanically embossing a surface covering without requiring the use of dedicated engraved or etched embossing plates and embossing rolls to deliver an in register embossed texture. Embossing rolls or plates used to mechanically emboss in register an imprinted design are expensive. Each new desired embossed pattern requires the manufacture of a new embossing roll or plate to deliver an embossed design which is in register with the printed design of the surface covering. Thus, there is a need for a mechanical embossing tool that can deliver an in register design without the need to create a new dedicated embossing roll, plate or belt.